/** @return ability mean */ public double abilityMean() { double mean = 0; for (Examinee examinee : objects) { mean += examinee.getAbility(); } return mean / objects.size(); }
/** * @return variance of sample of examinees * @throws Exception */ public double abilityVariance() throws Exception { if (objects.size() == 1) return 0; double mean = abilityMean(); double var = 0; for (Examinee examinee : objects) { double square = examinee.getAbility() - mean; var += square * square; } return var / (objects.size() - 1); }
@Override public int getId(Examinee object) { // TODO Auto-generated method stub return object.getId(); }